1. Field of the Invention
The present invention relates to a method for operating liquid-jet recorders to record images by flying liquid droplets formed by liquid-jet.
2. Description of the Prior Art
Recently ink-jet recording (liquid-jet recording method) attracts attention in that it generates very little noise, of such a degree as to be negligible, it makes high speed recording possible, and additionally it permits recording on plain paper without requiring special fixing treatment.
Among various liquid-jet recording methods, those described, for example, in Japanese Patent Application Laid-Open No. 51,837/1979 and German Patent Application Laid Open (DOLS) No. 2,843,064 are distinguished from other liquid-jet recording methods in that the driving force to eject liquid droplets in these methods is obtained by exerting thermal energy on a liquid.
That is, according to the recording methods disclosed in the above patent applications, a state change accompanied by a rapid volume increase is caused in a recording liquid by the action of thermal energy thereupon, and droplets of the recording liquid are ejected because of the state change, through an orifice in the front end of a recorder head to form flying droplets that are directed to a recording medium, thereby making a record.
In particular, the recording method disclosed in DOLS No. 2,843,064 is featured in that it can be applied very effectively to the so-called drop-on-demand recording method and in addition can give high quality images of high resolution at high speeds since it facilitates the realization of a full-line type of recorder head having densely aligned multi-orifices.
The recorder head used in the above-mentioned recording method is provided with (1) orifices for discharging droplets, (2) liquid flow paths which are in communication with the orifices, respectively, each of which flow paths includes a heat exerting section that applies thermal energy to the liquid so as to jet droplets of the liquid, and (3) electricity-to-heat converters (electric heaters) as a means of generating thermal energy.
Each electric heater has a pair of electrodes, on a support, and a heat-generating resistor layer comprising a heat-generating section in contact with the electrodes and therebetween.
Conventionally a liquid-jet recorder is operated by a driving system as shown in FIG. 1.
In FIG. 1, 4 is an electrode and 5 is a heat-generating resistor layer, which are connected to a power source 1. The flying droplets are formed by applying signals 3 to a switching element 2 that is, by the ON and OFF states of each switching element 2. The pair of electrodes 4 and the heat-generating resistor layer 5 are in contact with the ink filled in the corresponding liquid flow path, through a protecting layer (not depicted). This protecting layer is constructed of a material superior in properties such as heat resistance, liquid resistance, liquid-penetration preventive property, anti-oxidation property, breakage or flow resistance, etc., but no material completely satisfying in these properties has been obtained. In the above driving system, the heat-generating resistor layer and the electrodes often have positive potential and the ink has negative potential even for the moments when the driving is stopped. Hence, for instance, if a dielectric breakdown of the protecting layer occurs, an electro-chemical reaction will be caused between the electrode and the ink. This is responsible for significant shortening of the liquid-jet recorder life.